Chapter 14 Study Guide Burnett
Sources of Activation Energy
- Friction - Electric Spark - Light
Signs of Chemical Reactions (Does not guarantee a reaction)
- Gas Formation - Solid Formation - Energy Change - Color Change - FORMATION OF NEW SUBSTANCES THAT HAVE DIFFERENT PROPERTIES
Factors that affect rate of reaction
- Temperature - higher temperature causes a faster rate of reaction - Concentration - a high concentration of reactants causes a fast rate of a reaction - Surface Area - increasing the surface area of solid reactants increases the rate of a reaction - Presence of an inhibitor or catalyst
Balance these equations: 1. Fe+O2 → Fe2O3 2. Al+CuSO4 → Al2(SO4)3+Cu 3. Mg(OH)2+HCl → MgCl+H2O
1. 4Fe+3O2 → 2Fe2O3 2. 2Al+3CuSO4 → Al2(SO4)3+3Cu 3. Mg(OH)2+2HCl → MgCl2+2H2O
What type of reactions are these? 1. FeS + 2HCl -- FeCl2 + H4S 2. 2 Ag3N -- 6Ag + N2 3. P4 + 5O2 -- 2P2O5
1. double displacement 2. decomposition 3. synthesis
Exothermic Reaction
A chemical reaction in which energy is released
Endothermic Reaction
A chemical reaction in which energy is taken in
Rate of Reaction
A measure of how fast the reaction takes place
What are the products of a single displacement reaction?
A new compound and the replaced element.
Chemical Reaction
A process in which one or more substances change to make one or more new substances
What is a synthesis reaction?
A reaction in which 2 or more substances combined to form a new compound.
Decomposition
A reaction in which a single compound breaks down to form two or more simpler substances. Opposite of synthesis
Double-Displacement
A reaction in which ions from two compounds exchange places (one product is often a gas or precipitate)
Synthesis
A reaction in which two or more substances combine to form one new compound
Chemical Formula
A shorthand way to use chemical symbols and numbers to represent a substance
Inhibitor
A substance that slows down or stops a chemical reaction
Catalyst
A substance that speeds up a reaction without being permanently changed (not a reactant)
Synthesis can be represented by the equation: A+B--C. A and B can be elements or compounds and C is a compound. What equation could be used to represent a decomposition reaction?
C=A+B
How do catalysts differ from inhibitors?
Catalysts speed up the reaction while inhibitors slow down the reaction.
What is the force that holds two atoms together in a molecule?
Electromagnetic- ionic bond / strong- covalent
What is needed to break chemical bonds in the reactants?
Energy
How are exothermic reactions different from endothermic reactions?
Exothermic reactions release energy while endothermic reactions take in energy.
How do new substances form in a chemical reaction?
First, chemical bonds in the starting substances must break. Then, the atoms then rearrange, and new bonds form to make the new substances.
Naming Compounds
Ionic Bond: metal and non-metal - Add "-ide" ending to the non-metal ○ CaCl2 = Calcium Chloride Covalent Bond: non-metal and non-metal - 2nd element gets a prefix and takes an "-ide" ending - 1st element than 1 gets a prefix ○ H2O = Dihydrogen Monoxide ○ H3PO4 = Trihydrogen Phosphate ○ NH4+1 = Ammonium
Why can the product of synthesis reaction never be an element?
It can't because it is either elements or compounds combining which can only make a compound.
How does chewing your food well speed up the reactions in your digestive system?
It causes the food to have more surface area.
What does increasing surface area do to the rate of a reaction?
It increases the rate of reaction.
Why is the formation of a precipitate a possible indication of a chemical reaction?
It is a possible indication of a chemical reaction because a new substance was formed
The activation energy is always the energy gain between what two points on an energy diagram?
It is always between the reactants and the climax of the reaction.
What happens to the energy involved in an exothermic reaction?
It is released into the surroundings.
What happens to energy during an endothermic reaction?
It is taken in from the surroundings.
Prefixes (COVALENT)
Mono - 1 Di - 2 Tri - 3 Tetra - 4 Penta - 5
If iron replaces copper in Cu(NO3)2 is it more or less reactive than copper?
More
Ionic Compound Charge
Must equal 0
Does seeing a gas produced always mean a chemical reaction is occurring?
No, because it can just be a change of state. An example is a gas is given off when water boils.
Chemical
Of or having to do with the properties of actions of substances.
Synthesis Example
Sodium reacting with chlorine to produce sodium chloride
What happens in a chemical reaction?
Substances break apart or combine to form one or more new substances.
Which two reaction types can be considered the opposite of one another?
Synthesis and decomposition.
Two clear solutions are poured together and a blue precipitate forms. What type of reaction appears to have taken place?
Synthesis have because the solutions probably combined and formed a new compound.
What are the 4 ways substances react?
Synthesis, decomposition, single displacement and double displacement.
Hydrogen and chlorine react to produce hydrogen chloride. What bonds are broken an what bonds are formed during this reaction?
The bonds between the diatomic and hydrogen and chlorine atoms break and a bond forms between one hydrogen and one chlorine. Makes 2 HCl
Activation Energy
The boost of energy a chemical reaction must also get and is the smallest amount of energy that molecules need to react
What causes leaves to change color?
The chlorophyll breaking down to form new substances that have no color, so orange and yellow colors show.
Chemical Bond
The force that holds atoms or ions together
Explain why water boiling is not a chemical reaction, even though it releases a gas.
The gas released is just a change in state (a physical change not a chemical change)
What is the effect of temperature on reaction rate?
The higher the temperature the faster the rate of reaction.
Law Conservation of Energy
The law that states that energy cannot be created or destroyed but can be changed from one form to another
Law of Conservation of Mass
The law that states that mass cannot be created or destroyed in ordinary chemical and physical changes
What are the effects of higher concentration of reactants on reaction rate?
The reaction rate is faster.
Precipitate
The solid substance that is formed in a solution during a chemical reaction
Reactants
The starting materials in a chemical reaction
Products
The substances formed from a reaction
What happens when you mix water with baking powder?
The substances in baking powder react to form bubbles of carbon dioxide gas.
What happens to chemical bonds during a chemical reaction?
They break and form new bonds.
What must happen to reactant particles for a reaction to occur?
They must collide.
The equation below shows a combination of an element and a compound, but no single-displacement reaction occurs. What is the most likely reason this combination does not react? Ca2S2 + Al3 -- no reaction
This combination will not react because the changes of CaS and Al do not balance out and therefore are not able to react.
What happens to energy when a chemical bond forms? What happens to energy when a chemical bond is broken?
When a chemical bond forms, energy is released. When a chemical bond is broken, energy is taken in.
What happens to the chemical properties of substances during a chemical reaction?
When a chemical reaction takes place, the chemical properties of the new substance change from the properties of the old substances.
Single-Displacement
When an element replaces another element that is a part of a compound and makes a different element and a new compound
A scientist mixes substance A and substance B in a beaker. Neither substance A nor substance B can conduct electricity. The material in the beaker changes color, and the beaker becomes very hot. The material left in the beaker conducts electricity. Has a chemical reaction occurred?
Yes because the change in color and transfer of the thermal energy signs of a chemical change. Also, the new substance that is formed has different chemical properties than the original substances.
What are three types of energy that may be absorbed or released in a chemical reaction?
light, heat or electricity.
For an endothermic reaction,do reactants or products have more energy?
products
